An endoscope equipped with an infrared laser and a tiny mirror might one day help physicians diagnose early signs of cancer and other diseases and aid in surgery. A researcher at the University of Florida has designed a prototype device that captures images up to two millimeters beneath the surface of tissues, providing high-resolution, three-dimensional images at video-rate speeds.

In typical endoscopy, doctors thread a long, thin, camera-equipped fiber through a patient's airway or gastrointestinal tract to search out abnormalities. The images, displayed on a monitor in real time, can reveal signs of infection, internal bleeding, ulcers, and tumors on tissue surfaces. But today's endoscopes only show a superficial picture--they don't reveal what's going on under the surface, such as early tumor development.

"Eighty-five percent of cancers originate from the epithelium, which is about two millimeters deep," says Huikai Xie, associate professor of electrical and computer engineering and director of the Biophotonics and Microsystems Laboratory. In addition to its potential for detecting early signs of cancer, he says, the scope might prove useful as a surgical tool, helping surgeons determine how deep a tumor is embedded in tissue. "If you need to remove the tumor, the surgeons have a hard time determining when to stop. With a real-time, high-resolution tool, they will be sure."

John Saltzman, a gastroenterologist and director of endoscopy at Brigham and Women's Hospital, says such a technique would help identify early signs of cancer, particularly in the esophagus. In a condition called Barett's esophagus, for example, cells lining the esophagus undergo a change that increases the risk of cancer, says Saltzman, who is not involved in the research. "This technology would be an advantage for us to detect such abnormalities."

Instead of a tiny camera at the tip, Xie's endoscope is equipped with an infrared scanner and a tiny mirror, which scans tissue layer by layer to provide a three-dimensional image with microscopic resolution. The technique is based on a method called optical coherence tomography (OCT)--as a laser beams through the arm of an OCT scope, it hits tissue, and reflects some light back, while the rest scatters. Different tissues, such as cancer versus normal tissue, reflect light differently. An interferometer measures the reflected light and subtracts the scattered light. Altering the length of the arm alters the depth at which light is directly reflected back, producing images of different layers, which together form a three-dimensional image. The method is similar to ultrasound technology, and is often called "optical ultrasound."